Straightening of live human hair with an aqueous acidic glycol solution



Patented Dec. 9, 1969 iCC 3,482,581 STRAIGHTENING OF LIVE HUMAN HAIRWITH AN AQUEOUS ACIDIC GLYCOL SOLUTION John D. Weigand, 6445 Irving Ave.S.,

Richfield, Minn. 55423 No Drawing. Filed Aug. 1, 1966, Ser. No. 569,056Int. Cl. A45d 7/04 U.S. Cl. 132-7 Claims ABSTRACT OF THE DISCLOSUREStraightening of live human curly hair is accomplished by moisteningwith dilute aqueous acidic glycol solution followed by hot combing orpressing to dryness.

This invention relates 'to the treatment of hair and more particularlyto the straightening of normally curly hair. Although effective in thesoftening and straightening of hair having even minor curlingtendencies, the invention finds particular utility in the treatment ofsupercurly human hair.

Excessive curliness or kinkiness of human hair causes extreme difficultyin caring for the hair and scalp as Well as in styling. Many attemptshave been made to find means for overcoming this condition, and manytreatments have been described for more or less permanently removingpart or all of the curl of supercurly hair. Thus the hair may beforcefully straightened and heavily coated with stiff waxy pomades; orit may be softened, using more or less corrosive or caustic chemicalswhich must be neutralized after mechanical straightening of the hairshaft; or the temporarily straightened hair may be chemically treated toimpart water-resistance. None of these or other treatments has beenfound fully effective. Either the effect is lost on again shampooing thehair, or the hair itself is unduly weakened or its luster diminished ordestroyed, or the scalp is excessively irritated; or for various otherreasons the prior art methods and materials have not proven fullysatisfactory.

The present invention provides an improved treatment and treating agentfor hair with which superior results are achieved both in impartingsoftness and manageability to the hair and in maintaining these andother desired properties. The hair is strengthened rather than weakened,while its resistance to water is increased. The full natural luster isretained. No protective emollients 0r creams are required, yet the scalpis unharmed.

In its simplest form, the invention requires merely the application tothe clean hair of a dilute acidic aqueous solution of ethylene glycol orof 1,3-propylene glycol, followed by hot combing. The hair is promptlysoftened by application of the solution, so that it can be combedstraight and held in that condition. The solution, although acidic, issufficiently dilute to cause substantially no irritation of the scalpand presents no difficulty or inconvenience to the operator. Continuedcombing with a hot comb until substantial dryness is achieved thencompletes the process and results in straight or gently wavy hair.Unlike many treatments, the effect is relatively permanent, so that thehair may subsequently be shampooed a number of times without againreverting to the supercurly condition.

Straightening or relaxation of supercurly hair is accomplished at highconcentrations of glycol but at the expense of observable loss of lusteras well as a tendency of the hair to have a heavy, sticky or wet feel. Apreferred range for this component is about five to about ten percent ofthe total weight of solution, although concentrations as low as aboutthree percent and as high as about 20 percent are also useful. Thesolution contains sufficient acid catalyst to bring the acidity withinthe range of approximately pH one to three. Formic acid is found toimpart additional preliminary softness to the hair, and, althoughcompletely volatilizable, remains effective throughout the hot combingprocess; and this material is therefore preferred. Hydrochloric acid,p-toluenesulfonic acid, acetic acid and monochloroacetic acid have alsobeen found effective. Excellent results in the straightening ofsupercurly hair have been obtained with a solution of five parts byweight of formic acid and eight parts of ethylene glycol in 87 parts ofwater, the solution having a pH value of about 1 /2.

It will ordinarily be found helpful to add a small proportion of awetting agent to assist in obtaining rapid penetration and treatment ofthe hair. About one part of a material such as Ultrawet 60L Soft liquidorganic wetting agent in 2000 parts of the solution is illustrative.Ultrawet 60L is a biodegradable triethanolamine linear (C -C alkylatesulfonate liquid wetting agent. Although not required, various othercomponents such as emollients, scents or perfumes, coloring or tintingagents etc. may be added if desired. In all cases the additives aresubject to the requirement that they be inert toward the glycol and acidcomponents, and non-irritating to the user. Ultrawet 60L is described inU.S. 3,190,836 of June 22, 1965.

The glycols are known to be effective softeners for many natural andsynthetic fibers and might be expected to soften the hair; but sincethey are completely watersoluble the effect would logically be thoughtto be temporary only and to be lost on subsequent washing. Surprisingly,under acidic conditions and particularly when subjected to the elevatedtemperatures induced by hot combing, supercurly hair treated in this wayis found to be softened and straightened and to remain in this conditionthrough a number of subsequent washings.

In probable explanation of this important effect it is suggested thatthe hair is first softened and relaxed by the acidic aqueous glycolsolution and is then easily drawn out and straightened by the combingaction. As the treatment proceeds, esterification occurs between acidicgroups of the hair keratin and the primary hydroxyl groups of the glycolunder the influence of the acid catalyst at the elevated temperature,resulting in cross-linking between adjacent peptide chains. Thestraightened hair thus achieves a permanent set which is not relaxed nordestroyed upon subsequent washing. Consistent with such theory, it isfound that the more reactive primary hydroxyl groups of the short chainglycols, i.e. ethylene glycol and 1,3-propylene glycol, are required;the solution must be strongly acidic, i.e. at a pH of between 1 and 3,preferably about 1%; and the treatment must include hot combing orpressing, at comb temperatures of at least about 200 C., desirably at210 C. and preferably continuing until substantially no free glycolremains on the hair.

The following specific examples will further illustrate the practice ofthe invention, which however is not to be limited thereto.

EXAMPLE 1 Water grams 91.7 Ethylene glycol do 8.0 p-Toluenesulfonic aciddo 0.5 Wetting agent (Triton X-) drops 3 The pH of the solution is 1.7,i.e. about 1 /2.

EXAMPLE 2 Water grams 86.2 Ethylene glycol do 8.0 Formic acid (87%) do5.9 Wetting agent of Ex. 1 drops 3 pH 1.8

These solutions are applied to the freshly shampooed thoroughly rinsed,and fully or partially dried hair by padding, and the hair is thencombed, a few strands at a time, with a hot comb maintained at 210 C.until the hair feels substantially dry.

Triton X-100 wetting agent is identified as a biodegradablewater-soluble isooctyl phenoxy polyethoxy ethanol which contains 10moles of ethylene oxide.

What is claimed is as follows:

1. Method of treating clean live human hair comprising thoroughlywetting the clean hair with an acidic aqueous solution of volatileglycol selected from the class consisting of ethylene glycol and1,3-propylene glycol, and then hot combing the hair at a combtemperature of about 200 C.210 C.

2. A solution for use in the treatment of hair, consisting essentiallyof from about three to about 20 percent of a glycol selected from theclass consisting of ethylene glycol and 1,3-propylene glycol in anacidic aqueous solution at a pH within the range of about 1 to 3.

3. A solution as defined in claim 2 and including an .4 acid selectedfrom the class consisting of formic, acetic, monochloroacetic,hydrochloric and p-toluenesulfonic.

4. A solution as defined in claim 2 and containing about five to aboutten percent of said glycol and sufiicient formic acid to establish a pHof about 1 /2.

5. A solution as defined in claim 2 and including a significant smallamount, Within the range of about onehalf to about one and one-halfparts per thousand parts of said solution, of an organic wetting agent.

References Cited UNITED STATES PATENTS 2,389,755 11/1945 Baker 424-712,643,375 6/1953 Gant 132-7 ALBERT T. MEYERS, Primary Examiner V. C.CLARKE, Assistant Examiner US. Cl. X.R. 8-1275 1; 424-71

